Topical dressing

ABSTRACT

A topical dressing applicable to the body, as well as to the mucous membranes such as the oral cavity. The dressing or pharmaceutical preparation includes a physiologically active material, optionally combined with a solid, finely divided particulate carrier or inert material, and sufficient finely divided polytetrafluoroethylene (hereinafter referred to as &#39;&#39;&#39;&#39;PTFE&#39;&#39;&#39;&#39;) to form, after subjecting the materials to a working or kneading action, a flexible, coherent mass.

' United States Patent Vogt et al.

541 TOPICAL DRESSING [72] inventors: John W. Vogt, South Russell; Peter [2]] Appl. No.: 136,257 7 [52] US. Cl. ..l28/268, 128/296, 424/28 [51] Int. Cl. ..A6lf 7/02 [58] Field of Search ....424/22, 28, 56, 35]; 128/260, 128/268, 271, 156, 296

[56] References Cited UNITED STATES PATENTS 3,219,527 11/1965 Gurney ..424/28 51 1 Oct. 17, 1972 3,328,246 6/1967 Gottfried et al. ..424/28 3,339,546 9/1967 Chen 128/268 3,444,858 5/1969 Russell 1 28/268 Primary Examiner--Charles F. Rosenbaum Attorney-McNenny, Farrington, Pearne & Gordon and James A. Lucas [5 7] ABSTRACT A topical dressing applicable to the body, as well as to the mucous membranes such as the oral cavity. The dressing or pharmaceutical preparation includes a physiologically active material, optionally combined with a solid, finely divided particulate carrier or inert material, and ,sufficient finely divided polytetrafluoroethylene (hereinafter referred to i as PTFE) to form, after subjecting the materials to a working or kneading action, a flexible, coherent mass.

5 Claims, No Drawings 1 TOPICAL DRESSING BACKGROUND OF THE INVENTION A wide variety of products are currently available on the market in the field of wound dressings. For example, sterile and medicated gauze-type dressings are widely employed in hospitals after major surgery, as

. well as in the home for minor injuries. In spite of their wide acceptance, the gauze-type dressings are not without disadvantages. Usually, ,the desired medicament must be applied to the body prior to applying the gauze-type dressing, a procedure which is not difficult but is. time-consuming and inconvenient. When changes in the dressings are made, there is usually some adherence to the wound of wound exudate, which causes considerable discomfort to the patient. Moreover, the gauze-type dressings do not render the wound free of extraneous bacteria and viruses, nor do they control air and water vaportransmission to any predeterminable extent. I

Recently, various polymeric materials have been investigated for use in the treatment of wounds, burns, and other skin disorders. For example, collagen, PQlyvinyl alcohol, gelatin, and a wide variety of polymeric materials have been disclosed in the literature as being useful in the treatment of accidental and surgical wounds. However, in most instances, these materials do not control the growth, of bacteria successfully, and there have been serious problems with respect to patients who have been found to be allergic to some of these dressings.

Again with respect to the pre-spreading of the appropriate medicament, the unit dose is often critical inasmuch as an overdose is not only wasteful but can also result in irritation or injury, and an underdose is often ineffective. Particularly in view of the lack of skilled help in hospitals today, and much more so with respect to usage of these medicaments by the layman, it is advantageous to incorporate the medicament integrally with some type of bandage which can hold the medicament in place.

In yet another instance where a cataplasmic applicator is required in the control of hemorrhage resulting from extraction of a tooth, a number of specially designed'dental padsfor the application of a medication to 'a local-point within the oral cavity have been utilized. The instant dressing may be so formulated as to be a flexible, doughy, shapeable mass which can be tamped around the hemorrhaging area to control the hemorrhage by conforming anatomically to the area in which it is required. At the same time, the flexible,

doughy mass can be impregnated with whatever concentration of a particular medicament might be desired. After it has performed its function, it may be disposed of. With the doughy pad tamped in place, the patient has relatively free movement of his jaws, will not have the uncomfortable feeling of a wad of gauze which threatensto gag him, and the medicament will stay firmly in place. Thus, the hemostatic medication impregnated within the mass of the cataplasmic applicator will be kept in close contact with the area from which the tooth was extracted until it has performed its function.

V Most medicaments in topical dressings contain relatively minute amounts of active ingredients, since only a minute amount is required to accomplish the cure.

Thus, the active ingredient is usually combined with an inert carrier, and in cataplasmic applicators, the inert carrier is usually a solid. The instant invention is specifically directed to a cataplasmic applicator in which the major phase is finely divided, particulate solids less than 10 mesh in size and preferably in the size range from less than about 425 mesh to about mesh (Tyler), which solids are normally free-flowing when dry and agglomerate when wetted. It is upon these finely divided solids that an active ingredient is usually deposited in the desired concentration; on occasion, a material normally regarded as inert, such as talc, may be used by itself, as a protective barrier, as in the treatment of a burn.

With respect to the use of medicaments for stopping bleeding, called vasoconstrictors" or hemostatic medicaments, these are commonly used where rapid termination of bleeding is required for superficial cuts, particularly those in the face area. The most common example of such cuts are those which occur during shaving. To contend with this problem, liquid vasoconstrictors are available, but they have disadvantages. They are usually applied by impregnating a cotton wad with the liquid and then pressing the cotton against the out. Since this normally requiresv holding the cotton wad in place for some time, particularly early in the morning when time is of the essence, such applicators have not been very successful. An alternative is to incorporate the medicament ina gummy material which will adhere to the skin--a choice which is uniformly disregarded.

From the foregoing, it will be apparent that there are numerous problems associated with applying medicaments in the form of topical dressings and there have been a number of highly specialized forms of medicaments particularly developed for application in particular instances. Very few dressings perform all the functions of a dressing, and still fewer dlo so'conveniently. A dressing should provide protection from physical trauma; it should provide protection from infection by preventing exposure to air; it should prevent maceration; and finally it should maintain medicinal agents in contact with the wound. (Wound Healing, by Dr. P. Clarkson Bergamon Press, 1961) It is a peculiar property of the instant dressing that it can be formulated for any specificusage by varying the amount of PTFE in relation to the amount of solid particulate matter. Surprisingly, this is the only fluoro polymer with which the medicaments will form a coherent, flexible, doughy mass which is water vapor and gas-permeable, but relatively fluid-impermeable, which can have chemotherapeutic agents and other medicaments or additives incorporated therein, which can be easily removed from the skin because it has essentially no resistance to mechanical shock and tears easily, yet forms a barrier to bacteria and viruses.

SUMMARY OF THE INVENTION It has been discovered that a cataplasmic applicator may be formed by intimately mixing a medicament, optionally dispersed in an inert solid, particulate carrier material, with from about 0.1 to about 99 per cent by weight of the total composition of polytetrafluoroethylene, and working the intimate mixture to a sufficient extent to form a coherent, pliable, doughy mass.

It has also been discovered that by controlling the amount of polytetrafluoroethylene, the inert materials, the size range of the inert materials which can be chosen in a preselected cut in a range below Tyler mesh in size, and the amount of working to which the mass is subjected, the pliability of the end product may be tailored to any desired degree without becoming rigid.

It has further been discovered that the doughy mass formed as indicated hereinabove, in conjunction with a vasoconstrictor, and optionally with a liquid vehicle, may be used for dressing skin cuts which permit the cut to heal with part of the dressing incorporated therein,

while the rest of the dressing is easily torn away without any discomfort to the patient.

It has unexpectedly been found that a medicament kneaded into a pliable mass by incorporation therein of finely divided polytetrafluoroethylene, optionally in the presence of a liquid vehicle which may be inert oractive, provides a wound dressing which overcomes the disadvantages associated with the gauze-type and polymeric dressings, and is particularly useful because of its versatility in the treatment of cuts, burns and tooth extractions, in a variety of dermatological applications, and as a surgical dressing.

DESCRIPTION OF THE PREFERRED EMBODIMENT The instant cataplasmic applicator may be formed from any particulate material which has physiological activity, or to which physiological activity is imparted by incorporation therein of a suitable medicament, in intimate mixture with from about 0.1 to about 99 per cent by weight PTFE, based on the total weight of the mixture computed on a solids basis. Such a medicament may be any physiologically active material, whether it be solid, liquid, or gaseous, which contributes in any beneficial manner to the prevention, cure, or alleviation of disease, infection, pain, or contamination. The physiologically active material may be used by itself, or in conjunction with a carrier, or inert material. Such physiologically active materials include antibiotics, antiseptics, anaesthetics, antihistamines, vasoconstrictors, emollients, and the like.

The use of carrier materials which are generally inert will usually be found desirable, since the concentration of the medicament in the dressing will normally be relatively small. Inert carrier materials include talc, zinc oxide, bentonite, calcium carbonate, zinc stearate, and starch, among others. Waxes, petroleum jelly, and relatively high molecular weight vegetable oils may also be incorporated as liquid or semisolid vehicles, into the mixture, to provide the desired texture or other physical characteristics or to facilitate working of the mixture. Where, for example, a physiologically active material which is acidic in character is used in intimate mixture with talc and a wax, in addition to the desired amount of finely divided PTFE powder, a base may be included to buffer the acidic material, and vice versa.

When any of the above-mentioned physiologically active materials is worked with PTFE powder to form a pliable, doughy mass, it will be found to be non-adherent, and therefore, except where wedged into a specific cavity or held in place by some natural anatomical configuration, will require to be affixed in one form or the other. Where, for example, the instant cataplasmic applicator is to be used in conjunction with a vasoconstrictor on the face, it is found desirable to use it in conjunction with a Band-Aid-type strip of adherent material. On the other hand, where a poultice is to be used on a limb or on a part of the torso where a relatively large amount of the doughy mass is to be applied, it is preferable to bandage it in position. As mentioned hereinbefore, the PTFE, when used as a powder or as an emulsion, is the only known polymeric fluorocarbon material which will form such a doughy mass, despite the fact that there is essentially no moisture or liquid present in the cataplasmic applicator. Moreover, the instant PTFE-containing topical dressing is non-toxic, is a lubricant, has a velvety texture, and is one of the few materials known which does not cause allergy problems.

A particularly suitable powder of PTFE is the extrusion-grade powder sold by E. I. DuPont de Nemours & Co., as Teflon 6 powder. This powder has an apparent bulk density of 475 grams per liter, an average particle size of 500 microns, and a specific gravity of 2.23. An aqueous dispersion of PTFE, such as that sold by the above-mentioned company as Teflon 30 fluorocarbon resin, can also be used as a starting material in the present invention. This dispersion comprises a negatively charged hydrophobic colloid having about 60 per cent solids, consisting of particles having a size range from 0.05 to 0.5 microns, said dispersion containing a non-ionic wetting agent.

The amount of PTFE in the cataplasmic applicator may be varied from about 0.1 to about 99 per cent. The preferred range is from about 1 to about 10 per cent, and the use of additional amounts of PTFE'is found to be of little additional benefit, generally not justifiable by the concomitant additional expense. It will be found that, with an increase in the proportion of PTFE, the same degree of working will yield a doughy mass which has increased coherency. The cataplasmic applicator is characterized by the fact that it is easily torn and has little or no resistance to mechanical shock, and with increasing quantities of PTFE, the doughy mass formed my be shaped with finger pressure and will maintain its shape. This is especially important where it is usedas a dental pad, wedged or tamped into place where a tooth has been extracted.

The instant cataplasmic applicator is formed by placing the particulate materials in a mixing vessel, such as a Hobart blender, Brabender, kneading mill, or the like, where the mixing action is accompanied by a working action so as to knead the mixture. The PTFE powder,,either alone or dispersed in a liquid, or in emulsion form, is gradually added to the mixture while it is being worked at a temperature in the range from about 20 C. but below 200 C. The preferred working temperature is in the range from about 40 to about 100 C. After a short time, depending upon the particular apparatus used and the quantity of material to be worked, a doughy mass is formed which is coherent and pliable. Desired physiologically active materials may be added at the start, during mixing, or after the doughy mass has been formed.

A particularly useful form in which the instant applicator may be used is as an integral part of a cotton fiber or synthetic polymeric gauze wherein the doughy mass is pressed upon a plurality of layers of gauze, em-

bedding the gauze within the mass to an extent sufficient to provide the desired physiological activity of the applicator without permitting the wound to contact the gauze. Thus, a layer of poultice material is interposed between the gauze and the wound to prevent exudate from the wound infiltrating the gauze.

The following examples are illustrative of the invention. All parts referred to are parts by weight unless otherwise specified.

EXAMPLE I A mixture of 96 parts'by weight talc and 4 parts by weight of Teflon 6 polytetrafluoroethylene powder in sufficient mineral spirits to wet all the particles is slurried together at room temperature in a Waring blender. The slurry is filtered through a Buchner funnel to form a moist cake. This cake is rolled on an aluminum heated sheet using a Teflon-covered roller to form a coherent layer aboutone-eighth inch thick. The edges of the sheet are continually folded into the center during rolling, while additional mineral spirits are added to extend the plasticity of the sheet. After the solvent is removed by evaporation, the final product has adequate structural integrity and strength to permit it to be handled freely without crumbling. The product has a velvety texture and is used to cover a second degree burn to which it does not adhere.

EXAMPLE ll A topical dressing is prepared by mixing together 15 parts of a sulfa drug comprising equal parts of sulfacetamid'e, sulfadiazene and sulfamerazine and 4 parts polytetrafluoroethylene and 91 parts talc. The polytetrafluoroethylene is present as an emulsion of 2.2 milliliter of Teflon emulsion in 100 milliliter of water. A premix is made of the tale and sulfa powder, after which the premix is blended into the emulsion, using a spatula. The mixture forms a coherent mass in water and the mass is transferred to a hot plate maintained at a temperature of 150 F., on which it is rolled and folded into a thin, coherent sheet.

EXAMPLE Ill Another dressing suitable for a dental pad is prepared from a mixture of 50 per cent Teflon 6 polytetrafluoroethylene and 50 per cent talc, utilizing the same procedure described in Example I hereinabove. The manually rolled sheet, due to the high percentage of polytetrafluoroethylene, is substantially stiffer and stronger than the composite of Example l. Sections of the sheet are impregnated with medicaments, such as suitable concentrations of analgesics and vasoconstrictors for use as oral dressings.

Similarly, when equal amounts of talc and Teflon 6 PTFE powder are blended and worked in a pug mill maintained at about 40 C., along with minor quantities of medicaments, a relatively stiff, doughy mass is formed. Pieces of the worked material are useful as dental pads.

We claim:

1. A medicated cataplasmic applicator for topical application to a living body, comprising a flexible, coherent, doughy mass which is easily torn and has essentially no resistance to m ,chanical shock, formed by sub ecting an intimate, 801d, particulate mixture of physiologically active material, optionally in conjunction with a particulate carrier or inert material, and finely divided polytetrafluoroethylene optionally dispersed in a liquid or semisolid vehicle, to a blending action with sufficient working at a temperature in the range from about 20 but below 200 C., to form said applicator. V V g I V 2! The applicator of cla im 1, including in addition a cover sheet of thin material to maintain said applicator in contact with said living body.

3. The applicator of claim 1, wherein said particulate mixture is less than 10 Tyler mesh in size.

4. The applicator of claim 1, wherein said particulate carrier or inert material is selected from talc, zinc oxide, and bentonite.

5. The applicator of claim 2, wherein said cover sheet comprises a plurality of overlapping layers of a cotton fiber or synthetic polymeric gauze material embedded insaid applicator so as to provide a layer of applicator between said gauze material and the surface of the wound to which it is to be applied. 

2. The applicator of claim 1, including in addition a cover sheet of thin material to maintain said applicator in contact with said living body.
 3. The applicator of claim 1, wherein said particulate mixture is less than 10 Tyler mesh in size.
 4. The applicator of claim 1, wherein said particulate carrier or inert material is selected from talc, zinc oxide, and bentonite.
 5. The applicator of claim 2, wherein said cover sheet comprises a plurality of overlapping layers of a cotton fiber or synthetic polymeric gauze material embedded in said applicator so as to provide a layer of applicator between said gauze material and the surface of the wound to which it is to be applied. 